This invention relates to a magnetic recording device for recording information such as sounds and pictures on a recording medium formed of amorphous alloy such as rare-earth element-iron alloy which has magnetic anisotropy in a direction perpendicular to the surface thereof.
Conventionally, ring-shaped magnetic heads are used with e.g. magnetic discs in recording and reproducing information on a recording medium. In the use of such magnetic heads, track width cannot be narrowed without decreasing an S/N ratio at playback. Typical heads exhibit the narrowest allowable track width of scores of micrometers and thereabouts, so that they are unsuitable for high-density recording.
In order to increase the recording density, therefore, there has been developed a photo-magnetic recording system using light beams such as laser beams. Although capable of reducing the track width to approximately 1 .mu.m, this system is subject to the following defects. According to this photo-magnetic recording system, a light beam such as a laser beam, as well as a magnetic field perpendicular to the surface of a recording medium, is applied to the recording medium which is formed of amorphous alloy such as rare-earth element-iron alloy having magnetic anisotropy in a direction perpendicular to the surface thereof and temperature-dependent coercive force, and information is recorded on the recording medium by causing magnetic inversion in accordance with signals by means of the heat energy of the light beam. This system, however, requires a high-energy laser light source, so that the optical system including such light source will be large-sized, and the heat energy of light beams will possibly cause deformation of the recording medium. Moreover, when a light beam is applied to the recording medium for magnetic inversion, the temperature is gradually reduced from the center of the beam toward the periphery thereof to enlarge the magnetized region, so that the resolution of reproduced information may be deteriorated or the temperature distribution may vary with respect to the longitudinal and transverse directions of the track depending on the recording position on the medium, causing production of noise in the case of FM recording, for example. In order to obviate the latter defect, there is proposed a method for preventing enlargement of the magnetized region in the opposite direction to the direction of magnetic inversion (Japanese Patent Disclosure No. 80134/76). However, this method still involves a practical problem, that is, a technical difficulty in controlling the light beam and magnetic field applied to the recording medium within a delicate range of magnetic inversion.